Probing protoplanetary disk evolution in the Chamaeleon II region

¹ Univ. Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France
² European Southern Observatory, Alonso de Córdova 3107, Vitacura, Casilla 19001, Santiago 19, Chile
³ Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, USA
e-mail: marion.f.villenave@jpl.nasa.gov
⁴ Joint ALMA Observatory, Alonso de Córdova 3107, Vitacura 763-0355, Santiago, Chile
⁵ Unidad Mixta Internacional Franco-Chilena de Astronomía (CNRS, UMI 3386), Departamento de Astronomía, Universidad de Chile, Camino El Observatorio 1515, Las Condes, Santiago, Chile
⁶ Institute for Astronomy, University of Hawaii, Honolulu, Hawaii, USA
⁷ NASA Headquarters, 300 E Street SW, Washington, DC 20546, USA
⁸ Departamento de Ciencias Fisicas, Facultad de Ciencias Exactas, Universidad Andres Bello. Av. Fernandez Concha 700, Las Condes, Santiago, Chile
⁹ Núcleo Milenio de Formación Planetaria (NPF), Av. Gran Bretaña 1111, Valparaiso, Chile
¹⁰ Aurora Technology for ESA/ESAC, Camino bajo del Castillo s/n, Urbanización Villafranca del Castillo, Villanueva de la Cañada, 28692 Madrid, Spain
¹¹ Núcleo de Astronomía, Facultad de Ingeniería y Ciencias, Universidad Diego Portales, Av. Ejercito 441, Santiago, Chile
¹² National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, Virginia, 22903-2475, USA
¹³ Kapteyn Astronomical Institute, University of Groningen, Landleven 12, 9747 AD Groningen, The Netherlands
¹⁴ School of Physics and Astronomy, Monash University, Clayton, Vic 3800, Australia
¹⁵ Massachusetts Institute of Technology, Kavli Institute for Astrophysics and Space Research, Cambridge, MA 02109, USA
¹⁶ Universidad Técnica Federico Santa María, Departamento de Física, Avenida España 1680, Valparaíso, Chile

Received: 4 February 2021
Accepted: 22 June 2021

Abstract

Context. Characterizing the evolution of protoplanetary disks is necessary to improve our understanding of planet formation. Constraints on both dust and gas are needed to determine the dominant disk dissipation mechanisms.

Aims. We aim to compare the disk dust masses in the Chamaeleon II (Cha II) star-forming region with other regions with ages between 1 and 10 Myr.

Methods. We use ALMA band 6 observations (1.3 mm) to survey 29 protoplanetary disks in Cha II. Dust mass estimates are derived from the continuum data.

Results. Out of our initial sample of 29 disks, we detect 22 sources in the continuum, 10 in ¹²CO, 3 in ¹³CO, and none in C¹⁸O (J = 2−1). Additionally, we detect two companion candidates in the continuum and ¹²CO emission. Most disk dust masses are lower than 10 M_⊕, assuming thermal emission from optically thin dust. Including non-detections, we derive a median dust mass of 4.5 ± 1.5 M_⊕ from survival analysis. We compare consistent estimations of the distributions of the disk dust mass and the disk-to-stellar mass ratios in Cha II with six other low mass and isolated star-forming regions in the age range of 1–10 Myr: Upper Sco, CrA, IC 348, Cha I, Lupus, and Taurus. When comparing the dust-to-stellar mass ratio, we find that the masses of disks in Cha II are statistically different from those in Upper Sco and Taurus, and we confirm that disks in Upper Sco, the oldest region of the sample, are statistically less massive than in all other regions. Performing a second statistical test of the dust mass distributions from similar mass bins, we find no statistical differences between these regions and Cha II.

Conclusions. We interpret these trends, most simply, as a sign of decline in the disk dust masses with time or dust evolution. Different global initial conditions in star-forming regions may also play a role, but their impact on the properties of a disk population is difficult to isolate in star-forming regions lacking nearby massive stars.